Introduction Several methods have been suggested to measure anteversion of the cup component after total hip arthroplasty using simple anteroposterior (AP) radiographs. Herein, we compared six widely used anteversion measurement methods using two different AP radiographs (conventional pelvis AP vs. hip-centered AP) in order to identify the measurement method and radiograph that provide the highest accuracy and reliability. Methods We developed two custom-made bi-planar anteversion measurement models for the validation. Each model was designed for pelvis AP and hip-centered AP radiographs. The radiographs were acquired with both models’ inclination angle changing from 10° to 70° at 10° increments, and for each inclination angles, anteversion was changed from 0° to 30° at 5° increments. The measurements were obtained independently by two orthopedic surgeons blinded from each other using 6 methods: 1) Pradhan et al., 2) Lewinnek et al., 3) Widmer et al., 4) Liaw et al., 5) Hassan et al., and 6) Ackland et al. The measurements were repeated after 2 months. The accuracy, compared to the reference angle, and intra- and inter-observer reliabilities of each method were calculated. Results The highest accuracy was found when Liaw et al.’s method was used in hip-centered AP radiographs, which showed a difference of 1.37° ± 1.73 from the reference. Moreover, regardless of the type of the radiograph, the methods by Pradhan et al., Lewinnek et al., and Liaw et al. showed excellent correlations with the reference anteversion. However, substantial differences were found when the methods by Widmer et al., Hassan et al., and Ackland et al. were utilized, regardless of the type of radiograph used. When the anteversion was measured in the inclination between 30° and 50°, Pradhan et al.’s method in pelvis AP radiographs showed the highest accuracy (1.23° ± 0.92°). We also found no significant difference when the measured anteversions were compared between pelvis AP and hip-centered AP radiographs. Both inter- and intra-observer reliabilities were high for all measurements tested. Conclusions The methods by Pradhan et al., Liaw et al., and Lewinnek et al. may provide relatively accurate anteversion measurements with high reliability, regardless of the type of radiograph.

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The binding between receptor-activated nuclear factor kappa B (RANK) and its specific ligand (RANKL) during osteoclast development is an important target for drugs that treat osteoporosis. Recently, the leucine-rich repeat-containing G-protein-coupled receptor 4 (LGR4) was reported as a negative regulator of RANKL-RANK signaling that suppresses canonical RANK signaling during osteoclast differentiation. Hence, LGR4 agonists may be useful in inhibiting osteoclastogenesis and effectively treating osteoporosis. In this study, we used bone marrow-derived macrophages (BMDM) and a mouse model of RANKL-induced bone loss to investigate the effect of a RANKL-derived mutant, (MT RANKL), which was previously developed based on the crystal structure of the RANKL complex. In the present study, the binding affinity of wild-type (WT) RANKL and MT RANKL for RANK and LGR4 was determined using microscale thermophoresis analysis, and the effect of the ligands on the AKT-GSK-3β-NFATc1 signaling cascade was investigated using western blotting and confocal microscopy. In addition, the immunopositive expression of LGR4 and the colocalization of LGR4 and MT RANKL were analyzed in a mouse model of RANKL-induced bone loss. The results showed that in osteoclast precursor cells, MT RANKL bound with high affinity to LGR4, decreased AKT phosphorylation, and increased GSK-3β phosphorylation, resulting in the inhibition of NFATc1 nuclear translocation. In the mouse model, MT RANKL upregulated LGR4 expression, colocalized with LGR4, and inhibited bone resorption. These results indicate that MT RANKL, which is derived from RANKL and inhibits RANKL-induced osteoclastogenesis through an LGR4-dependent pathway, may be useful in the treatment of osteoporosis.

Introduction Number of methods has been suggested to measure anteversion in the simple AP radiograph and a few studies have validated their accuracy and reliability. In the current study, we compared six widely used anteversion measurement methods using two different radiographs (conventional pelvis AP vs hip centered AP) in order to determine which measurement method and which radiograph provides highest accuracy and reliability. Material and methods We developed custom made two planar anteversion measurement models for the validation. Each models are designed for Pelvis AP and hip AP. The radiographs were taken with the both models’ inclination changing from 10° to 70° at 10° increments and for each inclination angles, anteversion was changed from 0° to 30° at 5° increments. Therefore, the x-ray of the two models were taken in 49 scenarios. The measurements were done independently by two orthopaedic surgeons blinded from each other using 6 methods : 1) Pradhan et al, 2) Lewinak et al, 3) Widmer et al, and 4) Liaw et al. 5) Hassan et al, 6) Ackland et al. Result The highest accuracy was found when Liaw method was used in hip centered AP radiograph which showed difference of 1.37° ± 1.73. Also, regardless of the type of the radiographs, Pradhan, Lewinnek, Liaw all showed relatively high accuracy. However, substantial difference was found when Widmer, Hassan, Ackland method were utilized regardless of the type of radiograph used. When the anteversion were measured in the inclination between 30° and 50°, Pradhan’s method in pelvis AP showed the highest accuracy (1.23° ± 0.92°). Also, we found no significant difference when measured anteversions were compared between Pelvis AP and hip centered AP. Conclusion The study indicates that the Pradhan, Liaw and Lewinnek method may provide the relatively accurate anteversion measurement regardless of the type of the radiographs. Also, it would be unnecessary to take the hip centered AP radiographs in addition to the pelvis AP radiographs for the purpose of measuring anteversion.